A recording device called the Electronically Activated Recorder (EAR) is described. The EAR taperecords for 30 sec once every 12 min for 2-4 days. It is lightweight and portable, and it can be worn comfortably by participants in their natural environment. The acoustic data samples provide a nonobtrusive record of the language used and settings entered by the participant. Preliminary psychometric findings suggest that the EAR data accurately reflect individuals' natural social, linguistic, and psychological lives. The data presented in this article were collected with a first-generation EAR system based on analog tape recording technology, but a second generation digital EAR is now available.